This invention relates to a resin-coated pipe and, more particularly, to a resin-coated pipe, which has a resin composition excellent in the processibility and is excellent in the mechanical strength, impact resistance at normal and low temperatures, heat resistance, chipping resistance and coating surface appearance.
Resin layers for resin-coated pipes are generally required to be excellent in the mechanical strength, impact resistance at normal and low temperatures, heat resistance, chipping resistance and coating surface appearance and also excellent in the processibility.
Heretofore, polyethylene obtained by high pressure process and ethylene-vinyl acetate copolymer have been used as a resin layer for resin-coated pipes. These materials, however, are inferior in the chipping resistance. The chipping resistance is a very important property in view of the protection of pipes, particularly steel pipes, used in outdoor places exposed to small stones or the like flying thereto. Coating resins which are obtainable by cross-linking high pressure process polyethylene or ethylene-vinyl acetate copolymer with peroxides or through electron beam irradiation are comparatively satisfactory in the chipping resistance. These resins, however, require a separate step of thermal shrinking at the time of coating the steel pipe. The coating process is therefore time-consuming, and thus the mass productivity is inferior.